Process for the manufacture of ethers



June 2z, 1948. H. MGUINOT mL 2,443,906

. PRocEss Fon` THE MANUFACTURE op ETHERS Filed March 17, 1945 Gas llchol f 1 A :222:55: 4 Ether jroth breaker a ""Dd-- vessel /1 ashes Patented June 22, 1948 PROCESS Fonrrnn MANUFACTURE oF E'mERs Henri MartnfGuinotQ Versailleaand Jean Gardas, Saint-RomansJes-Melle, France, yassignors to Les Usines De Melle (Societe Anonyme),

Saint-Leger-les Mella France France, a company of Application March .17, 1945, serial No. '583,377

e In France March 26, 1943 4 Claims.

It iswell known that the classic method of manufacture of sulphuric ether through catalytic dehydration oflalcohol by means` of sulphuric liquors lentails difficulties as a consequence of by-reactions which are detrimental to the yield:

(ci. zsm-614) 2 l f t,

richer with'watei'. "It `is then necessary tores'ort to enamelled vesselsbut the latter have an insuicient heating surface and enamel scales off y readily.

for instance productionof ethylene due to theV fact that the etherify'ing reagent is too strong, and formationof sulphurous acid from sulfuric acid' lwhich is reducedV by organic materials `in the reactant medium. Both reactions are always accompanied with a more or less eccentuated browning `of the etherifying bath, which discloses other undesirable by-reactions, such as resinification of acetaldehyde transiently formed by oxidation of alcohol.

In industrial practice, etherifying baths are generally a mixture of equal volumes of sulphuric acid of 66 B. and of 96.6 per cent alcohol (i. e. 70 parts by weight of acid for'30 of alcohol);

At first, such a mixture has avery good activity provided water and `ether are taken away byk We have now found that when working in accordance with the conventional method without any entrainer, it is possible to do away welththe.` above drawbacks, provided oneuses baths'which contain a relatively large, predetermined propors tion of water, owing to which lead is no longer corroded and becomes i-lt for lining purposes. As a matter of fact, we have unexpectedly found that as concerns corrosion,` everything happens as y though the titre of sulphuricacid, i. e. the ratio sulphuric acid: sulphuric acid-l-water,V is concerned alone and the actual proportion of alcohol and ether in the mixture vpractically plays no part in thisrespect. Thus very concentrated sulphuric acid is always offensive, even where distillation in proportion to their being formed.`

However, the use of such a mixture does notl allow of completelyavoiding the above mentioned icy-reactions; any slight variation in theper-v centage of alcohol or in the temperature of the etherifying mixture Causes a considerable' increase of the amounts of ethylene andsulphurous acid, with strong blacking ofthe bath. y e

Besides, lead generally'forming the inner lining of the etherifying boiler is severely corroded,

so that it is not unfrequent to find it out of user after less than 24 hours; at least, the purity of ether is not always good. 1 i

In order to do away with these disadvantages,` it has been proposed to operate in quite anhydrous medium, by adding tothe etherifying bath a hydrocarbon adaptedto play the part of a Water entrainer. Reaction equilibriumis then constantly shifted in a direction favourable to rapid etherication and it is possible towork at.

alowertemperature;

This method enables of obtaining a very llarge activity oi the etherifying bath; vit is possib1e,. for instance, to obtain in a continuous process, a daily amount of ether vattaining 15 times the weight ci the bath in with a temperatureof etheriiication not higher than 115 to 120 C.

However, let alone an increased consumption of steam, a drawback of the method is that the use or lead should beprohibited as it is lacted upon by anhydrous sulphurc acid; likewise special steels should be avoided as they are rapidly corroded when after ups and downs oflany kind duringdistillation, the bath grows momentarily I diluted in a large proportion of alcohol and ethexx On the other hand, an acid having a titre low` er than '75 to 80 per cent is practically without any action on lead in the conditions of tempera-`I ture adopted. We have further found that in contradistinction with any expectation, `these baths relatively rich in water are stillcapable of causing etheri- 'cation of alcohol at a sulicient rate. Thus,` 60. per cent sulphuric acid mixed with so much alcoV hol as to secure a boiling point of- 130 C. (i. en 5 per cent by weight) yields an etherifying bath capable of producing every day in a continuous process, one time and a half itsweight of ethen With per cent acid the production reaches 4 times the weight of the bath, assuming that the sametemperature of C. has been obtained; by adding l2 per cent by weight of alcohoLy With '10 per cent acid admixed with 20 per cent by weight of alcohol, the daily amount of ether produced is more than 6 times the weight offthe v bath, when working at 130 C. l l Y :i

Practically it is advisable to use 65 to '70 per cent acid'so as to keep a good margin: `for safety against corrosion of lead. It is then only necessary to rectify the vapors evolving out of the etherifying vessel with a view to separating ether from accompanying alcohol and water.;` `The proper Acomposition of the bath once determined, it is necessary to keep this compositionunaltered in a continuous process in order to avoid an accidental accumulation of water,` which would cause the reaction speed quickly to fall, asV well as a failure of water, even momentary, which would cause incipient corrosion of lead and gen- @ration of. ethylene and sulphur dioxide. To

this end, a substantially constant heating of the etherifying vessel being provided, the temperature of the bath is adjusted to the predetermined value (practically 125 to:` 130 C.)N by controlling the rate oijalcohol supply; and water' is sent back to the etherifying vessel by a proper amount to keep a constant volume of bath; any substantial:

The etherifying bath is little coloured and after several weeks of full-rate work, it has only alight brown hue.

. As to: ether, its7 purity is substantiallyA higher than that of: the product obtained according, to.Y

the, classic method. `It is slightly hydrated: (0.7. to 0.8 per cent) and includes only traces of. acid,` aldehydeand peroxides. No traceoi sulphurous compounds isl found; with Nesslers reagent, it gives only aV light yellow tint, while, the ether obtained by the classic method generally gives veryy quicklywith this'vr reagentV aA dark brown and veryl often a1 black coloration.

The. following description.. withreference to the appended drawing given. solely by way oi example will! better show how. this. invention. may be, car-v The drawing is.. a diagrammatic View. of, asuit.- able apparatus for carrying. outour method.

In' the' etherifyingboiler-|, of. a. capacity. of 1200.: litres, provided with a heating: device 2, we poured 1000 kg. of, 68 per centsulphur-iic.y acid together with' the necessary amount of alcohoL to bring theboilingzpoint: of the mixture near` 130 C.,

thatiste-say about 1-801l;g. While-the mixture boiled-we continuously introduced alcoholfrom tank 4 into boiler I through pipe 3 at the requiredy rate. Alcohol was' previously'passed throughs a scrubber I5;, the purpose. of wl1ich..will herein.

afterA4 be explained. The. vapors7 from. boi-ler' I` lrst passedthrougn afoam-breaker. 5, theny interA the middle" part'. of? the col-umn 6;, which: was heated. at its baseat and; in which. the; vapors were: rectiied'.` From the upper part oi said; column, af few: plates underthe top, vapors: or ether-were drawn oulrthroughpipes. After condensations atY llgfether wasfcollected in, a tankv lli: VolatileI impurities, particularly" acetaldehyde, were gathered?. onA the upper.` plates' ot` cnlumn'y 6- after` condensation at- II, were` withdrawn from'- I.t2-atlthezproper;rate; `Vlfaterproduced during: the'V reaction-,Wasn withdrawn` through'. pipe IY3'.' froml the base parti of,` the column;

As for uncondensabl'e' gases essentially consisting; of' small amountsf. of; ethylene formed: during thereaction', they evolved` from condenser: I-Il through: pipe I'lll These gases being'V saturated with ether vapors: to `beV recovered, Weref delivered; tof aV rst scrubber I5; where they were washedv with alcoholv fede to boiler' I,A then to; second scrubber |61 where; any -alcoholf carried. along` was recovered byv means't ofV water sprinkling: therethrough;y Ethylene free` from soluble products escaped" throughI pipe I 'I' and could4 be stockedi in a: gasom'eter. l

In". order'to ease upv condenser; I I: which; workedy ina unfavourableJ conditions by: reasonf. of.v thee lowl temperature". of; the; vapors td be condensedg. lt:

4 was found advantageous to provide an auxiliary condenser I8 for cooling vapors drawn through pipe I9 from a point at about the 2/3 of the height of. the column? said vapours. being. amixture of ether'and ,alcohol` A parti ofr'liquid condensed at I8 was returned through pipe 20 to the plate just below pipe I9, the remainder being sent back to boiler I through pipe ZI.

I'ni order tozsecure a constant proportion of Water in the etherifying bath, a pipe 22 provided .withA a cock, allowed. us to return to boiler I a partei" thev washingA water from scrubber I6. It isialsopossibleto.. use for this purpose a part of Iihehotl Washes leaving the base of column 6 at I3. Said washes; may be supplied to vessel I through pipe 23. provided with a control cock as shown;

` It` should be understood that our invention is not conned to the use of the apparatus above described, as this description has been made only as a non-limitative example.

The ether` obtained in accordance with our methodlis characterized, as already set forth, by

ar higher purity. than, thatof the product made according toI classic. method; consequently it is particularly adapted to be. usedlas a raw material for. production ofanaesthetic ether.

While we have described. our invention in detail, the embodiment given in the description and the, drawing being. only for example. it will be obvious to those skilled in the art, after understanding our invention, that various changes and modifications may be made. therein without departing from the spirit orscope thereof.

What we claim is:

l..4 Acontinuous process for the production of ether, whichA comprisesboiling in a reaction zone a-.mixture of alcohol and an aqueous solution of sulphuric. acid having a strength in the range of -to 80 per cent inv such a relative proportion that the mixture boils at a. temperature inthe range of about m-1359 C., thus producing gas and vapors Iin said. reaction. zone; continuously removing, said. gas and vapors substantially wholly and,in-,uncondensed-lcondition from said reaction zone without reux; and continuously adding alcoholv andV water to said mixture in calculated proportionsyto keep saidstrengthA and temperature substantially constant within said ranges.

2;` The. process of claim 1, further comprising the. steps ofiA separating' saidgas and vapours in asecond Zonee separatefromv said reaction Zone, into gas, waten, ether and a substantially anhydrous mixture of ether and' alcohol; and continuously returning said mixture of ether and: alcohol toV said reaction zone;

3'.. 'Ifhei` process of claim 1, further comprising. thestepsof introducingsaidgas andfvapours into the-middle-'portionof a distillation zone so as to cause'gatheringl ofl water in the bottom part ofV saidf. distillation zone, a substantially anhydrousether-alcohol mixture at a point in'- saidxdistillation zone above the point of introduction of said gas-and vapours, pure anhydrous ether above said ether-alcohol mixture in said distillation zone,

having; a strength` inthe range of V 60 to. 80 per centg. the; step of' continuously adding: Water in. a;

2,443,906 5 calculated proportion to compensate for steam evolution and keep said strength within said JEAN GARDAIS.

REFERENCES CITED 1()- The following references are of record in the file of this patent:

UNITED STATES PATENTS range, to a boiling mixture of said alcohol and Number Name Date said aqueous solution in such a, relative propor- 1,482,804 Mann Feb. 5, 1924 tion that said mixture boils at a temperature in 5 1,537,161 Lihtenthaeler June l, 1926 the range of about 120 to 135 C. 1,733,721 Carter Oct. 29, 192.9 HENRI MARTIN GUINOT. 1,868,076 Ricard July 19, 1932 

